Image construction system using multiple arrays of drop generators

ABSTRACT

Arrays of laterally spaced orifices, all communicating with a liquid pressure supply, all subjected to vibration at the same frequency to separate the liquid jets into streams of individual drops, provide a system for locating all of the drops with a predetermined space-time correlation, by depositing the drops on a receiving element which has relative movement with respect to the arrays at a speed correlated to the drop generation rate, or by irradiating the drops in space at a predetermined time to make them visible. Uses include printing multiple copies from a master, high-speed printout from a computer or memory, and creation of variable three dimensional visible shapes for study.

United States Patent lnventors Richard P. Taylor;

Russell H. Van Brimer, Fred E. Culp,

Chillicothe, Ohio Appl. No. 768,790 Filed Oct. 18, 1968 Patented Feb. 2,1971 Assignee The Mead Corporation Dayton, Ohio a corporation of OhioIMAGE CONSTRUCTION SYSTEM USING MULTIPLE ARRAYS OF DROP GENERATORS 9Claims, 7 Drawing'Figs.

U.S. Cl l78/6.6, 346/75, 346/33, 40/106.21

Int. Cl H04n 1/22 Field of Search 346/75,

140; 178/66, 30, 25; 317/3; l01/(lnquired), 93RC; 40/106.21, 106.22(lnquired); 35/(Inquired) CONTROLS Primary Examiner-Joseph W. HartaryAttorneyMarechal, Biebel, French & Bugg ABSTRACT: Arrays of laterallyspaced orifices, all communicating with a liquid pressure supply, allsubjected to vibration at the same frequency to separate the liquid jetsinto streams of individual drops, provide a system for locating all ofthe drops with a predetermined space-time correlation, by depositing thedrops on a receiving element which has relative movement with respect tothe arrays at a speed correlated to the drop generation rate, or byirradiating the drops in space at a predetermined time to make themvisible. Uses include printing multiple copies from a master, high-speedprintout from a computer or memory, and creation of variable threedimensional visible shapes for study.

PATENTEDF EB 2m: 3,560,5d1

' SHEET 1 BF 3 RICHARD P; TAYLOR. RUSSELL H. Van BRIMER a 9y FRED E.CULP ATTORNEY PATENTED FEB 2|97l SHEET 2 BF 3 oooovm FIG-7 TIMINGCONTROL PATENTEUFEB zlsm $560,641

sum am 3 FIG-5 SHIFT 70 E 70 E E 70 REG. I

- l6 x 20 I MATRIX I '1 CHARACTER I I J LL mum LULALLUL LU] J T|M|NG 75SWlTCHlNG- ANY OF 88-!6 LINE INPUTS ig-53:0 UNIT "'TO ANY OF l32-l6 LINEOUTPUTS FROM so 1 BUFFER v 1 H -+i-. h 11W I 4 H IMAGE CONSTRUCTIONSYSTEM USING MULTIPLE ARRAYS OF DROP GENERATORS CROSS REFERENCE TORELATED APPLICATIONS This application is related to copendingapplications entitled IMAGE CONTROL SYSTEM WITH SCANNING DROPGENERATORS, Ser. No. 768,800, HIGH SPEED PRECI- SION PLACEMENT OF LIQUIDDROPS, Ser. No. 768,767, IMAGE RECONSTRUCTION SYSTEM, Ser. No. 803,910,and COORDINATE PLACEMENT OF INK DROPS, Ser. No. 768,766 all filed ofeven date herewith and assigned to the same assignee.

BACKGROUND OF THE INVENTION This invention relates to systems in whichdiscrete uniformly sized drops of fluid, for example a marking fluidsuch as ink, are projected in a controlled manner to achieve apredetermined space-time correlation. A typical use of the invention isin high-speed printing wherein the drops are selectively placed on apaper web moving at relatively high speed past a drop generating device.It is proposed that the drop generating device include a plurality ofarrays of orifices from which common size drops are projected at acommon frequency. Selected drops are switched or deflected intocatchers, while the remainder follow their trajectory to create apattern in space and time. A typical use of the invention is inhighspeed printing where the drops are deposited on a moving web, thuscreating a two-dimensional print in timed relation with web movement.

The prior art has suggested various ways of producing the uniformlysized and synchronously generated drops, a typical example being asystem such as disclosed in the US. Pat. to Sweet et al., No. 3,373,437.Little attention has been given, however, to drop space-time correlationor to packing a large number of orifices in near enough proximity topermit solid area printing by parallel digital switching. In printing,for example, if the drops are to be placed precisely both vertically andhorizontally to form a desired image or pattern there must be a definiterelationship between the rate of drop generation and the paper movement,and this relationship should in turn be correlated to the spacingbetween adjacent drops to be deposited on the paper.

The situation is complicated by physical demands ofthe drop generatingassembly and array. The orifices must be spaced apart a certain minimumdistance in order to accommodate the charging and deflecting electrodes,and also to accommodate the catcher system into which some drops aredeflected. As a result, it has been found from the practical standpointthat the spacing between orifices in an array, under the confinement ofphysical sizes and dimensions, is substantially greater than is desiredin order to deposit the relatively small drops, in the order of 0.003 to0.005 inch, adjacent to each other. In the ideal case, in order to forma completely solid image, it is necessary that the dots adjoin orslightly overlap each other, or at least are placed so closely side byside that there is no apparent background between them. It has beenpossible to generate drops which produce a deposit of this size throughorifices having a diameter in the order of 0.001 inch, however his notpossible to space these orifices and associated parts from each other bythe relatively few thousandths of an inch required in order to achievethe desired result.

SUMMARY OF THE INVENTION The present invention relates to a method andapparatus by means of which a plurality of drops of fluid, such as amarking substance, can be selectively projected and closely spaced intimed spatial relation. In a particular embodiment the movement of asheet or web is correlated to drop generation from several arrays, suchthat solid coverage over substantial areas of the sheet or web can beachieved by reason of the adjacent or slightly overlapping position ofthe drops deposited on the surface.

This is accomplished by the use of a plurality of arrays of dropgenerating devices, each of which extends transversly of the directionof movement of the sheet or web, and each of which includes dropgenerating orifices and associated control equipment for the individualdrops from each orifice, arranged in predetermined spaced position. Themultiple arrays are mounted offset with respect to each other such thatdrops emanating from the arrays will deposit along predeterminedinterlaced and relatively thin laterally spaced, lengthwise bands orstrips. It is thereby possible to obtain coverage of the entire crosssection of the sheet or web. By correlating the drop generation ratewith drop size and with paper advancement rate, it is possible todeposit successive drops in each of the above-mentioned strips incontrolled closely spaced positions whereby each band or strip can befilled with an essentially continuous deposit.

By timing drop switching signals in accordance with paper advancementrate and with the longitudinal spacing of the orifice arrays, it ispossible to create an intelligible drop deposit pattern. For highresolution in the drop deposit pattern, it is possible tophase-synchronize drop generation with drop switching thereby depositingeach drop at an accurately centered position within a predetermined dropdeposition matrix.

By applying intelligence signals to the control electrodes of theindividual drop generating units in each of the arrays, it is possibleto control the deposit of any given drop over the entire area of theweb. Considering an image area or pattern to be produced on the web orsheet, each drop generated by each array is destined for a particularcell or coordinate position, in an x--y matrix of the image or pattern,on the sheet or web, and whether or not that particular drop reaches itscell depends on the intelligence imposed on the corresponding controlledelectrodes. In other words, the intelligence signal determines whetheror not a drop is desired at each particular xy coordinate, anddetermines whether or not the drop is deflected or permitted to depositon the sheet or web as the portion of the image or pattern beinggenerated.

In one embodiment of the invention, an image to be created on the sheetor web can be formed from a master placed in an optical scanner. Theelectro-optical pickup of the scanner includes an individual sensor forevery xy coordinate of the image matrix. Each sensor is in turnconnected to a corresponding control electrode in one of the arrays, andthrough proper coordination, the scanner produces the intelligencesignals which control the deflection, or lack of it, resulting inproduction of an image or pattern on the web passing the arrays. It willbe appreciated that the scanner should have sensors spaced and staggeredaccording to the arrangement of the arrays and their individualorifices, or suitable electrical delays should be introduced to producethe same result.

It is of course possible to use for the receiving surface individualsheets of paper or other suitable material, or a relatively longcontinuous web can be used. Furthermore, the invention has particularand unique utility with regard to marking or printing on irregularsurfaces. This is true because the irregularities of the surface, unlessthey be very deep with respect to the travel of the drops, have littleeffect upon the horizontal deposition pattern of the drops. Thus, aprint made on an irregular-surface such as sandpaper, various textiles,or wavy surfaces as of corrugated paper, can be achieved with greaterclarity and much less difficulty than with conventional printing methodswhich require contact of an inked plate or other member with thematerial to be imprinted. Also, the shape of the arrays need not belinear, but can be curved or shaped to relate to the configuration ofthe receiving element. As examples, successful results have beenobtained printing on sandpaper and corrugated medium; other typicalapplications include printing or marking on bottles,,cans, and othercontainers.

The present invention also includes a printer output for electronic dataprocessing equipment. It is possible to generate printed material, suchas text material, at high speeds with the equipment provided by thisinvention, for example speed in the order of 2,000 feet per minute webtravel. As a typical example, using characters of ordinary typewritersize, it is possible to print in the order of 300,000 characters persecond, using a web speed in the order of 2,000 feet per minute andproducing characters of pica size in lines of up to 22 inches lengthwith a maximum of about 132 characters per line.

It is clear from the foregoing that a device constructed according tothe invention has the capability of producing characters at an extremelyhigh rate, comparable to the output of an electronic data processingmachine. For example, the character generation rate previously mentionedis capable of handling the output of a computer through a bufferinterface arranged to control directly the various deflection electrodesin the arrays of the system. The computer output can also bemagnetically or otherwise recorded, and used to drive the input of thesystem.

The invention is not limited to printing or creating of patterns.Controlled placement of liquid drops on a receiving surface is usefulalso in operations such as etching, coating, particularly over selectedareas of the receiving surface, and optical recording or plotting, aswell as in processing or fabrication of multiconstituent products.

It is also possible to produce variable three-dimensional displays,using a plurality of arrays, in-line or staggered, and using controlover the individual drops to locate them in a pattern, then irradiatingthe drops at a predetermined time, as by high-speed flashes of lightwhich are timed with reference to some beginning of drop generation. Thecontrol over drop generation enables the resulting three-dimensionaldisplay to be changed in shape or size within limits of the system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representationof a printing system embodying the present invention, wherein theseveral drop generating arrays are driven through suitable amplifiersfrom an electrooptical scanning device on which a master of the image orpattern to be reproduced is scanned, and in which the image or patternis reproduced repeatedly on a traveling web of paper;

FIG. 2 is a diagrammatic illustration of the manner in which portions ofseveral characters are simultaneously created through control of thedrop generating equipment of a single array;

FIG. 3 is an enlarged diagram showing the orifice and deflectionequipment incorporated within a single drop generating and controllingunit;

FIG. 4 is a schematic electrical diagram illustrating the manner inwhich a single drop generating and controlling device functions;

FIG. 5 illustrates a typical printout unit using the principles of theinvention;

FIG. 6 is a diagram illustrating the related deposit of drops fromsuccessive arrays; and

FIG. 7 shows a variable three-dimensional display system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, andparticularly to FIGS. l4, which illustrate one preferred embodiment ofthe invention, for purposes of explanation the receiving element ontowhich the pattern or image is to be created, for example repetitively asin a printing operation, is shown as a web of paper 10 from a supplyroll 12 passing over supporting structure such as a table 13, past pinchroll 15, and onto a takeup roll 16. Over the table 13 there are aplurality of arrays of fluid drop sources or projectors, each of whichincludes a plurality of orifices through which the liquid is expelled ina stream which is broken into individual drops. For purposes ofexplanation the first array is shown as uppennost, and the web 10 passesfirst beneath this array, then next to an array 22 of identicalstructure, and thence past additional arrays 24 and 26. The web andtable are shown broken between the arrays 22 and 24, signifying that thenumber of arrays is variable, depending upon the desired result.

The liquid substance to be placed precisely on the web 10 is suppliedfrom a reservoir or tank 30 through an output conduit 32 and through afilter 33 to a manifold arrangement 35 which, as shown, apportions andsupplies each of the arrays with the liquid under pressure. A vibratordevice, such as a supersonic vibrator, is indicated schematically at 37and is attached to the liquid supply piping in order to impose a highfrequency vibration on the entire liquid supply system.

The liquid from the supply piping is directed to a cross manifold ineach of the arrays, for example to the manifold 38 of the array 20, andthese manifolds in turn have a large number of small orifices 40 (FIG.3) from which a fine liquid stream is expelled. As a result of the highfrequency vibration, the stream rapidly breaks into individual dropswhich are accordingly spaced. In a typical embodiment the orifices 40are each of a size in the order of 1.5 mils, and the resultant drops areof a size in the order of 3 mils diameter. Drops of this size typicallyproduce circular printed dots having a diameter of about 5 mils.

The drops are projected in the form of a jet or stream toward the movingweb 10. For essentially full coverage of a longitudinal strip of 5 milwidth, consecutive droplets from the strip generating orifice should bedeposited with a center-tocenter dot spacing of about 3.5 mils or less.Since the time between consecutive drops is equal to the reciprocal ofthe stimulation frequency, the foregoing requirement may be convertedinto a design specification for the drop stimulator. The equation is V Iq where V is the velocity of the moving web, d is the desiredcenter-to-center dot spacing, and f is the required stimulationfrequency. Assuming a web velocity of about 400 inches per second, theabove stated conditions result in a required stimulation frequency ofabout l20 kHz.

In a system of this type in order to cover an 8 -inch wide image area onthe web, 1,600 orifices are required spaced on centers 5 mils apart. Thephysical demands of this system are such that the orifices cannotreadily be arranged in a continuous row transversely of the sheet, hencein order to accommodate the necessary spacing between orifices intotheir physical size and the size of the related control equipment, theorifices are instead spaced apart a substantially greater distance ineach array, and these orifices preferably are evenly spaced, and thearrangement is the same in each array, with the individual arrays beingoffset such that the orifices track over separate bands or strips alongthe sheet and fill with respect to each other in such a manner that ifall of the orifices are continuously operating and all drops arepermitted to strike the surface of the web, the web will be fullycovered across the 8 -inch image web. The arrangement is illustrated inFIG. 2, which shows the beginning of the creation of the letters M andE, with certain of the streams of drops from selected orificesdepositing on the web as it moves beneath the first array 20.

In order to control the deposition or nondeposition of the drops eachdrop which it is desired not to deposit is electrostatically chargedbycontrolling a potential applied to the charge ring 42 spaced in thecontrol structure immediately below the orifice 40. Downstream of thecharging electrode is a set of deflecting electrodes 44 which provides acontinuous deflecting field operating to deflect charged drops from thestream into a catcher unit 45 which includes a blade 46 projectingoutward adjacent, but not intercepting the stream path of the uncharged,and hence not deflected, drops. The drops that are deflected into thecatcher accumulate and are recirculated to the reservoir through areturn line 48, a segment of which is shown in FIG. 2.

The charge applying electrode 42 thus functions as a means forselectively charging drops which are not to be deposited on the web, andtogether with the deflecting electrodes 44 and the catcher 45, theseparts function as a means for moving from the drop stream those dropswhich are not to deposit on the web or other receiving element. Thesystem is thus binary, in that absence of a charge results in a droppassing directly to and depositing on the web, whereas presence of acharge results in deflection instead of deposition.

As shown in FIG. 3, it is preferred that the web and the stream of dropsintersect at an angle. This angle is so selected that the velocitycomponent parallel to the direction of web travel at the point of impactof the drops approximately equals the velocity of the moving web 10. Ithas been found that this arrangement results in minimum deformation ofthe drop as it deposits on the web, and hence results in a dot which isessentially circular in shape on the web.

Referring back to FIG. 1, one form of input for the system, in which apattern or image can be reproduced over and over on the web, is in theform of an optical image storage, such as a photograph or like print, ora photographic film on which the nonimage areas are transparent and theimage areasare opaque. This film is mounted on a drum 50 which istransparent, and inside the drum is a suitable lamp 52, whereby lightpassing through the nonimage areas of the film is arranged to actuate areading means in the form of a bank of photosensors 55, corresponding innumber and in spacing to the orifices 40 in the first array 20.Preferably a plurality of optical fibers (not shown) are arranged acrossthe drum 50in spaced positions corresponding to the arrangement of theorifices in a corresponding array, and the fibers conduct light tocorresponding ones of the photosensors. Light actuating thesephotosensors is thus translated into electrical signals which aresuitably amplified through the amplifier circuits 60, details of whichare shown in FIG. 4, and the amplifier outputs in turn are applied tothe individual charging rings 42 for each of the control unitscorresponding to each of the orifices in the array. Therefore, actuationof a particular photosensor will result in applying a charge to itscontrol ring 42, thereby deflecting that drop into the catcher systemand preventing deposition of that drop on the web 10.

There are a number of banks of photosensors, indicated by the referencenumbers 57, 58 and 59, corresponding in number to the arrays 20...26,and the spacing of the photosensor banks around the drum 50 correspondto the spacing of the arrays along the path of the moving web 10. Tocoordinate the reading means with the printing or depositing function,the drive motor 61 for the drive drum and the drive motor 62 for therecord drum 50 are actuated and carefully controlled through controlcircuits 65 which maintain these drives in synchronism, or alternativelydrive drum l5 and record drum 50 may be driven by a common shaft.

It is also possible to utilize the capability of the abovedescribedsystem as a high-speed printer for data processing machines. The printermay be controlled from a memory, such as magnetic tape storage or corememory, or in some instances the printer may be driven directly from theoutput of the computer through buffer units which act to relate thecomputer output signals to the necessary signals for operating this formof printer.

As an example, assuming as previously mentioned, a web speed of 2,000feet per minute or 400 inches per second, and assuming that clots may begenerated with 1.5 mil orifices which are in the order of 5 milsdiameter on the web, it is possible to generate standard typewriter sizecharacters of approximately 80 mils width and 100 mils height, using 16jets for each character, in other words requiring l6 orifices and theiraccompanying controls.

Assuming the need for a printer corresponding to presently availablehigh-speed mechanical printers, a capacity of 132 columns, equal to aline of 132 character capacity, can be generated by using signals fromthe input to identify the character to appear in each column. A standardtypewriter font has available 88 different characters, (these can beidentified using a seven-bit code) and with a standard line spacingproducing lines six to the inch, at the web speed specifiedapproximately 417 microseconds are available from the start of one lineto the start of the next line. In this time the printer must have thecapability of buffering in and being prepared to generate up to 132possible characters. Assuming that the seven-bit code is employed forcharacter identification, the requirements are to accept and process inthe order of 1,000 bits of information in about 410 microseconds. Thisis within the present capability of known switching and bufferingdevices.

As seen in FIG. 5, the 88 characters can be produced by 88 diodematrices such as diode matrices shown diagrammatically at 70, eachhaving 20 horizontal rows and 16 vertical subcolumns. Corresponding tothe 132 character columns are 132 printing heads 72, each of which maybe connected by switching unit to any matrix 70. Each printing head 72contains 16 orifices corresponding to the 16 vertical subcolumns in thatmatrix to which the printing head may be connected.

All matrices 70 are simultaneously scanned in timed, verticallyprogressive steps. For each step every matrix 70 dumps 16 binary bitsinto switching unit 75. As a result thereof, each orifice control ring42 is actuated by 20 sequential binary signals corresponding to thecoded information in one vertical subcolumn of that matrix 70 to whichthe parent printing head 72 may be connected. This in turn producessimultaneous, vertically progressive printing of up to 132 characters.At the end of the 20-step sequence, switching unit 75 connects eachprinting head 72 to the matrix 70 which is programmed for that characterwhich is next scheduled for printing by the subject printing head.

The above-described vertical matrix scan is produced by a 20-stage shiftregister 77 which in turn is actuated by timing unit 80. Timing unit 80is also connected to each of the printing heads 72 and serves as aconstant frequency control for drop stimulation in all of the orifices.In this manner there is achieved a one-for-one correspondence betweengenerated drops and drop switching signals. For this example therequired stimulation frequency is about kHz. and the resulting printingrate, assuming a character in every column is 316,800 characters persecond.

Because of previously discussed packaging considerations, it isdifficult, if not impractical, to build printing heads 72 insingle'array configurations of 16 orifices each. Again, in accordancewith the practice of this invention the orifices are staggered in aplurality of arrays as shown in FIG. 5. As shown in the FIG., however,the center-to-center orifice spacing is about'*20 mils. In practice, ifeven this spacing is difficult to achieve, a convenient working modelmay utilize heads with 16 orifices staggered one behind the other inarrays of one orifice each. As an alternative it is feasible to use anarrangement as shown in FIG. 1. Such an arrangement would employ 16arrays with 132 orifices per array. The arrays would be electricallyconnected such that at any given time corresponding orifices in the 16arrays would all be connected to the same matrix 70. Thus the 16corresponding orifices would be the equivalent of one printing head 72as illustrated in FIG. 5.

In order to accommodate the above described physical separation of theorifices it is necessary to make a corresponding adjustment in theorifice switching controls. Referring to FIG. 1, it may be observed thata laterally transverse line on web 10 will pass first under orificearray 20 and thence under each of the other arrays; the transit timefrom array to array being related to the speed of the web and to thelongitudinal separation of the arrays. Therefore, it becomes apparentthat if compensation is made for the above transit time, then theorifice arrangement comprising a plurality of staggered andlongitudinally displaced arrays can be treated as functionallyequivalent to a single array with all orifices combined-side-byside inextremely close proximity.

FIG. 6 illustrates the geometry of this situation. The FIG. shows twoorifices 91 and 92 which are representative of members of staggeredarrays; that is, the orifices are mutually offset in a direction normalto the plane of FIG. 6. It may be observed that a drop leaving orifice91 simultaneously with a similar drop from orifice 92 will travel for adistance b and strike web at a distance d behind the latter drop. Inorder to place two drops such as drops 93 and 94 precisely side-by-sideon web 10, drop 94 must have a delayed release time. That is, thecontrol electronics for the orifices in the front array must operate ina time domain which lags that of the rear array by a time T where:

or T= i c080 where c is the array spacing distance and 6 is the webintercept angle as illustrated.

Thus, by building an appropriate time delay into the control electronicsfor the forward array, the two arrays may be programmed and switched asthough they were combined into a single array with a double number oforifices. Obviously this concept can be extended to any number ofarrays. For a typical web printer as shown in FIG. 1 there may beemployed as many as such arrays. This would permit each array to have anorifice-to-orifice spacing of about 0.1 inch and result in drop depositpatterns staggered at 5 mil intervals across the printing area.

It should be appreciated that the required control delays for aplurality of staggered arrays may be obtained in many ways. In thisregard, storage and retrieval from a shift register is the equivalent ofstaggered optical sensors modeled after the jet orifices and scanning acontrol or master image.

It should be appreciated, furthermore, that precise drop depositionrequires phase control of the stimulation at every orifice. In practicethis may be difficult to achieve. However, for many applications it isadequate merely to provide master timing control for all charge rings42. Then as long as all orifices are stimulated at the same frequency,each switching charge will catch the desired number of consecutivedrops. Since the separation moments for corresponding drops from thevarious orifices will be randomly distributed throughout one stimulationcycle, the impact points for these drops will be randomly scatteredalong longitudinal lines of length $.Thus

open loop stimulation produces a slight degradation in systemresolution.

Referring to FIG. 7 which shows schematically an arrangement forproducing variable three-dimensional displays, at the top of the FIG.there are a plurality of closely arranged arrays, indicated by thegeneral reference numeral 85. It will be understood that each arrayconsists of a large number of individual drop generating units (such asshown in FIG. 4, for example). These arrays are closely stacked andregularly spaced, such that drops from each generating unit will fallalong a predetermined path, precisely spaced with respect to each other,as indicated by the vertical lines in FIG. 7. Since the individual dropgenerating units can be controlled to project drops at a regular andhigh frequency, if cross currents of air or the like are eliminated, asby operating in a vacuum or under reduced pressure and controlledconditions, then the drops will project in the same regularly spacedpositions toward the catching basin 87 shown at the bottom of FIG. 7. Ifa single drop generating unit is switched to the on" condition, andcontinues to generate drops at regularly spaced intervals for apredetermined time, these drops will proceed in a trainlike mannertoward the lower catch basin 87.

At any given time, these drops will be located in space with respect totheir point of origin in the drop generating unit and with respect toeach other. It is possible therefore to time the switching of theindividual unit such that the drops will be in the form of a patternedline or sequence proceeding vertically downward from the origin at thedrop generating unit. Multiplying this arrangement many times, it isthus possible to have a plurality of such vertical drop patterns allprecisely related to each other, since the generating unit can beexcited at the same high frequency. Therefore, if such an arrangement beproduced under controlled light conditions, for example, it is possibleto irradiate the drops at a predetermined time, for

example by using high-speed flashes of light, to make.atthreedimensional pattern visible to an observer.

For example, the plurality of arrays shown in FIG. 7 is surrounded bythe number of high-speed flash lamp units These can be of conventionaldesign, sometimes referred to as stroboscopic flash lamps, andpreferably are arranged to fire simultaneously, thereby projectinglightfrom a number of different directions toward the falling drops from thearrays. The speed of the light flash is in the order of a microsecond,thus it is possible to stop" the flight of the drops insofar as theobserver is concerned. A suitable timing control, shown schematically at95, programs the unit such that initiation of a plurality of droppatterns from the various drop generating units starts a time sequence,and when a desired number of drops have fallen in a predeterminedpattern, to a predetermined point, the flash lamps are triggered toilluminate the resultant pattern and essentially fix it in space, so faras the observer is concerned, due to persistence of vision. Theoperation can be repeated at high speeds a number of times.

For example, one can compare the operation to a moving picture displaywhere repetition in the order of 16 frames per second, coupled with thevisual persistence of the viewer, produces an image which appears to beeither stationary, or to move in a regular manner. By controlling theoperation of the individual drop generating units it is thus possible toproduce a three-dimensional display which can be essentially static, andviewed from many different angles, and which can be varied by changingthe programming of the drop generating unit. This enables an observer tochange the shape of the threedimensional display as he may desire. Sucha device is usable in studying various shapes for purposes of mechanicaldesign, artistic design, in the study of mathematical problems dealingwith complex three-dimensional objects, or topographical problems, toname just a few uses.

From the foregoing, it will be apparent that each of the embodimentsdescribed includes a plurality of arrays of drop generators, allstimulated from a common vibration source. Each generator hasa'switching means to permit deflecting of selected individual drops fromtheir normal trajectory, thus providing the capability to generate apattern by locating the remaining drops in predetermined space-timecorrelation,

under the control of a data matrix which responds to some masterintelligence such as a memory and buffer input to the" system.

While the method herein described, and the forms of apparatus forcarrying this method into effect, constitute preferred embodiments ofthe invention, it is to be understood that theinvention is not limitedto this precise method and forms of apparatus, and that changes may bemade in .either without departing from the scope of the invention.

We claim:

1. The method of creating a pattern on a receiving member stant speedsuch that successive drops in any jet will. deposit on the member inadjoining positions whereby a continued deposit of successive drops willproduce an essentially continuous line lengthwise of the receivingmember;

cause each jet to break into individual drops, the stimulation fre f =&where V,, is the velocity of the stimulating each of such jets at acommon frequency t0.

receiving member and d is the center-to-center spacing of adjoining dropdeposits; and

. switching selected ones of said drops from their respectivetrajectories and removing such drops from the system and thus causingthe remaining drops to form a pattern of predetermined configuration.

The method of claim 1, wherein step (d) includes:

. scanning a master representation of the pattern to be reproduced;

. creating digital control signals from the scanning operation; and

g. and employing the signals from step (f) to control the switching step(d).

3. Apparatus for controlled placement in space and time of repetitiouslygenerated liquid drops comprising:

a plurality of arrays of orifices for generation of a plurality of rowsof liquid jets each directed along a specific trajectory related to theother jets;

all of said orifices having the same exit area and parallel nozzle axes;

the orifices in each of said arrays having a common centerto-centerspacing and the arrays being laterally staggered for production ofinterleaved adjoining drop deposit patterns across a receiving membermoved successively past said arrays, adjoining drop deposits beingspaced by a predetermined center-to-center distance (d);

liquid supply means operative to provide all said orifices with liquidat the same pressure thereby providing drops of uniform size andparallel jet trajectories with drops having a common velocity;

means for producing drop stimulation at a common frequency (f) in all ofsaid jets;

switching means including a charging device for each jet arranged tocharge selectively predetermined ones of the drops according to a masterintelligence input and deflecting means cooperating with said chargingdevices to switch drops from their respective trajectories according tothe charge status of the individual drops;

means for removing drops of one charge status from the data transfermeans for generation of a data matrix in response to a masterintelligence input and connected to produce a visible display of saidmatrix by control of said switching means; and

transport drive means operative to move a receiving member such as a webpast said arrays at a constant velocity (V,,,) matched to the dropstimulation frequency (f) and the drop size such that the frequency isrelative to the web velocity and drop deposits according to f ingmember.

5. Apparatus according to claim 3 and further comprising a plurality ofrows of sensors arranged in spaced positions corresponding to thearrangement of said arrays and means for transporting a representationof said master intelligence input past said sensors at a velocitycorresponding to the velocity of the receiving member.

6. Apparatus as defined in claim 3, comprising:

a plurality of rows of photosensors corresponding in number andarrangement to said jets;

means for transporting a representation of the master intelligence pastsaid banks of photosensors;

means for directing radiant energy to which said photosensors respondagainst said representation of the master intelligence for modificationof the energy before it reaches said photosensors,

switching controls responsive to individual ones of said photosensorsand connected to corresponding ones of said charging devices; and

a drive for said transporting means coordinated to said transport drivemeans to cause a one-to-one reproduction of elemental areas of saidmaster intelligence on said receiving member.

7 Apparatus for the rapid precise placement of small drops of liquid ina pattern of predetermined width on a receiving member continuouslymoving in a direction lengthwise of the pattern, comprising:

a supply of liquid under pressure;

a plurality of arrays of laterally spaced orifices extending across thepattern width of said receiving member, all of said orificescommunicating with said liquid pressure supply to develop a series ofliquid jets directed in parallel equidistant paths towards saidreceiving element and said arrays being staggered to produce aninterleaved pattern of adjoining drop deposits;

stimulator means imposing on all the jets continuous vibration at apredetermined frequency to cause each of said liquid jets to break intoindividual drops identical as to size and velocity and equally spacedfrom each other;

means moving the receiving member to intersect the drop paths at aconstant velocity so related to the stimulation frequency thatsuccessive drops from the same orifice will make adjoining dropdeposits, whereby each drop remaining in each path is deposited in apredestined and different coordinate position on the receiving member;

charging means for selectively applying a charge to each drop in all ofsaid series as each drop is formed;

means providing a deflection field along and normal to the drop pathsbetween said charging means and said receiving member;

means controlling said charge applying means to cause differentialcharging on a binary basis of corresponding drops in each of said jetsat the same instant;

means for diverting the drops having one charge condition and allowingthe drops having the other charge condition to continue along the normaljet path to deposit on the receiving member; and

said means controlling said charge applying means including:

a support for a master representation of the pattern,

reading means having a plurality of sensors corresponding in number tothe number of orifices in said array,

said reading means being mounted to scan the entire width of saidmaster,

driving means synchronized to said means for moving the receiving memberand connected to cause relative scanning movement between said mastersupporting means and said reading means at a rate correlated with themovement of said receiving member, and

individual control connections between each of said sensors andcorresponding ones of said charge applying means.

8. Apparatus as defined in claim 7, wherein:

the master to be reproduced is an optical representation of the pattern;

said supporting means including a rotatable cylinder;

said reading means including a plurality of optical fibers arrangedacross said cylinder in spaced positions corresponding to thearrangement of the orifices in said arrays,

said sensors comprising a plurality of photoelectric transducers, eachone receiving light from a corresponding one of said optical fibers; and

said driving means being connected to rotate said cylinder past theopposite ends of said optical fibers.

9. Apparatus for the rapid precise placement of small drops of liquid ina pattern of predetermined width on a receiving member moving in alengthwise direction, comprising:

at least two arrays extending laterally across the width of said patternand in predetermined spaced relation with each other in the longitudinaldirection of movement of the receiving member;

a source of liquid under pressure connected to each said array;

a plurality of laterally spaced orifices in each array communicatingwith said liquid pressure supply to develop a series of laterally spacedliquid jets directed along parallel equally spaced paths toward saidreceiving member;

said jets being spaced laterally from each other by a distance greaterthan the minimum spacing desired for adjacent areas on said receivingmember,

the locations of the jets from one array being offset laterally fromthose of another such that drops deposited from different arrays areinterleaved with each other to cover side-by-side bands lengthwise ofsaid receiving member;

means for imposing on all the jets continuous stimulation at apredetermined frequency to separate said liquid jets into a plurality ofstreams of individual drops identical as to size and velocity and spacedapart to form successive drop deposits at the same spacing as thespacing between adjacent bands;

switching means for selectively applying electrostatic charges toselected drops from the jets of both of said arrays;

means for deflecting each charged drop from its jet and allowing theuncharged drops to deposit in predetermined locations on said receivingelement; and

means for moving a receiving member past the arrays at a constant speedequal to the drop generation frequency times the center-to-centerspacing of adjoining drop deposits whereby each drop is destined for apredetermined coordinate location on the receiving member and the actionof said switching means determines the fonn of pattern created bydeposited drops on the receiving member.

1. The method of creating a pattern on a receiving member such as asheet or web by selective spatial and positioned control over a largenumber of small liquid drops, comprising the steps of: a. generating aplurality of rows of liquid jets all directed along paralleltrajectories in space, each row of jets having equally spaced jets andthe rows being laterally staggered to produce an interleaved dropdeposit pattern across the receiving member with the drop depositsadjoining; b. moving a drop receiving member past the jets at a constantspeed such that successive drops in any jet will deposit on the memberin adjoining positions whereby a continued deposit of successive dropswill produce an essentially continuous line lengthwise of the receivingmember; c. stimulating each of such jets at a common frequency to causeeach jet to break into individual drops, the stimulation frequency f dwhere Vw is the velocity of the receiving member and d is thecenter-to-center spacing of adjoining drop deposits; and d. switchingselected ones of said drops from their respective trajectories andremoving such drops from the system and thus causing the remaining dropsto form a pattern of predetermined configuration.
 2. The method of claim1, wherein step (d) includes: e. scanning a master representation of thepattern to be reproduced; f. creating digital control signals from thescanning operation; and g. and employing the signals from step (f) tocontrol the switching step (d).
 3. Apparatus for controlled placement inspace and time of repetitiously generated liquid drops comprising: aplurality of arrays of orifices for generation of a plurality of rows ofliquid jets each directed along a specific trajectory related to theother jets; all of said orifices having the same exit area and parallelnozzle axes; the orifices in each of said arrays having a commoncenter-to-center spacing and the arrays being laterally staggered forproduction of interleaved adjoining drop deposit patterns across areceiving member moved successively Past said arrays, adjoining dropdeposits being spaced by a predetermined center-to-center distance (d);liquid supply means operative to provide all said orifices with liquidat the same pressure thereby providing drops of uniform size andparallel jet trajectories with drops having a common velocity; means forproducing drop stimulation at a common frequency (f) in all of saidjets; switching means including a charging device for each jet arrangedto charge selectively predetermined ones of the drops according to amaster intelligence input and deflecting means cooperating with saidcharging devices to switch drops from their respective trajectoriesaccording to the charge status of the individual drops; means forremoving drops of one charge status from the jets; data transfer meansfor generation of a data matrix in response to a master intelligenceinput and connected to produce a visible display of said matrix bycontrol of said switching means; and transport drive means operative tomove a receiving member such as a web past said arrays at a constantvelocity (Vw) matched to the drop stimulation frequency (f) and the dropsize such that the frequency is relative to the web velocity and dropdeposits according to f d and the deposit areas of successive dropsissuing from the same orifice will adjoin on the receiving member. 4.Apparatus according to claim 3, said data transfer means comprisingtiming means for delaying switching commands to jets in successivearrays by amounts correlated to the longitudinal displacements of thearrays with respect to the path of motion of the receiving member andthe velocity of the receiving member.
 5. Apparatus according to claim 3and further comprising a plurality of rows of sensors arranged in spacedpositions corresponding to the arrangement of said arrays and means fortransporting a representation of said master intelligence input pastsaid sensors at a velocity corresponding to the velocity of thereceiving member.
 6. Apparatus as defined in claim 3, comprising: aplurality of rows of photosensors corresponding in number andarrangement to said jets; means for transporting a representation of themaster intelligence past said banks of photosensors; means for directingradiant energy to which said photosensors respond against saidrepresentation of the master intelligence for modification of the energybefore it reaches said photosensors, switching controls responsive toindividual ones of said photosensors and connected to corresponding onesof said charging devices; and a drive for said transporting meanscoordinated to said transport drive means to cause a one-to-onereproduction of elemental areas of said master intelligence on saidreceiving member.
 7. Apparatus for the rapid precise placement of smalldrops of liquid in a pattern of predetermined width on a receivingmember continuously moving in a direction lengthwise of the pattern,comprising: a supply of liquid under pressure; a plurality of arrays oflaterally spaced orifices extending across the pattern width of saidreceiving member, all of said orifices communicating with said liquidpressure supply to develop a series of liquid jets directed in parallelequidistant paths towards said receiving element and said arrays beingstaggered to produce an interleaved pattern of adjoining drop deposits;stimulator means imposing on all the jets continuous vibration at apredetermined frequency to cause each of said liquid jets to break intoindividual drops identical as to size and velocity and equally spacedfrom each other; means moving the receiving member to intersect the droppaths at a constant velocity so related to the stimulation frequencythat successive drops from the same orifice will make adjoining dropdeposits, whereby each drop remaining in each path is deposited in apredestined and different coordinate position on the receiving memBer;charging means for selectively applying a charge to each drop in all ofsaid series as each drop is formed; means providing a deflection fieldalong and normal to the drop paths between said charging means and saidreceiving member; means controlling said charge applying means to causedifferential charging on a binary basis of corresponding drops in eachof said jets at the same instant; means for diverting the drops havingone charge condition and allowing the drops having the other chargecondition to continue along the normal jet path to deposit on thereceiving member; and said means controlling said charge applying meansincluding: a support for a master representation of the pattern, readingmeans having a plurality of sensors corresponding in number to thenumber of orifices in said array, said reading means being mounted toscan the entire width of said master, driving means synchronized to saidmeans for moving the receiving member and connected to cause relativescanning movement between said master supporting means and said readingmeans at a rate correlated with the movement of said receiving member,and individual control connections between each of said sensors andcorresponding ones of said charge applying means.
 8. Apparatus asdefined in claim 7, wherein: the master to be reproduced is an opticalrepresentation of the pattern; said supporting means including arotatable cylinder; said reading means including a plurality of opticalfibers arranged across said cylinder in spaced positions correspondingto the arrangement of the orifices in said arrays, said sensorscomprising a plurality of photoelectric transducers, each one receivinglight from a corresponding one of said optical fibers; and said drivingmeans being connected to rotate said cylinder past the opposite ends ofsaid optical fibers.
 9. Apparatus for the rapid precise placement ofsmall drops of liquid in a pattern of predetermined width on a receivingmember moving in a lengthwise direction, comprising: at least two arraysextending laterally across the width of said pattern and inpredetermined spaced relation with each other in the longitudinaldirection of movement of the receiving member; a source of liquid underpressure connected to each said array; a plurality of laterally spacedorifices in each array communicating with said liquid pressure supply todevelop a series of laterally spaced liquid jets directed along parallelequally spaced paths toward said receiving member; said jets beingspaced laterally from each other by a distance greater than the minimumspacing desired for adjacent areas on said receiving member, thelocations of the jets from one array being offset laterally from thoseof another such that drops deposited from different arrays areinterleaved with each other to cover side-by-side bands lengthwise ofsaid receiving member; means for imposing on all the jets continuousstimulation at a predetermined frequency to separate said liquid jetsinto a plurality of streams of individual drops identical as to size andvelocity and spaced apart to form successive drop deposits at the samespacing as the spacing between adjacent bands; switching means forselectively applying electrostatic charges to selected drops from thejets of both of said arrays; means for deflecting each charged drop fromits jet and allowing the uncharged drops to deposit in predeterminedlocations on said receiving element; and means for moving a receivingmember past the arrays at a constant speed equal to the drop generationfrequency times the center-to-center spacing of adjoining drop depositswhereby each drop is destined for a predetermined coordinate location onthe receiving member and the action of said switching means determinesthe form of pattern created by deposited drops on the receiving member.